1. Technical Field
This invention relates to personal cooling devices and, more particularly, to a combined clothing garment and air-cooling device for reducing a user body temperature during physical activity.
2. Prior Art
When the environmental temperature is below the body temperature, heat is transferred from the body through one or more heat transfer mechanisms of radiation, conduction, convection and/or evaporation of water from the body. This forces the body to conserve heat and increase heat production. When the environmental temperature is above the body temperature, heat is transferred into the body through one or more heat transfer mechanisms of radiation, conduction, and/or convection. In this situation, for example, the body uses the evaporation of perspiration from the skin and the evaporative cooling from exhaled moisture to maintain the core body temperature.
The body takes an active role in regulating the body temperature. The temperature of the body is regulated by neural feedback mechanisms that operate primarily through the hypothalmus. The hypothalmus contains not only the control mechanisms, but also the key temperature sensors. Under control of these mechanisms, sweating begins almost precisely at a skin temperature of 35 degrees C. and increases rapidly as the skin temperature rises above this value. The heat production of the body under these conditions remains almost constant as the skin temperature rises.
Different regions of the body have different abilities to transfer heat. This is based in part on both the surface area of the body region and the relative vascularization of the body region. For example, up to 40% of the body's heat is lost from the head. This is due to the large blood supply to the head, the extra surface area of the head, and from water evaporating from the nose and mouth. This proves to be particularly problematic when a person must remain in extremely hot temperatures with a covered head. Football players, military workers, and construction workers, to name a few, are often required to wear helmets or hard hats for protection, even in the most extreme temperatures. This prevents heat from escaping the body and may lead to heat stroke or other dangerous outcomes.
Clothing is used to help maintain the body core temperature. For example, additional layers of clothing are worn to help maintain body temperature in cold environments. Conversely, fewer layers of clothing are worn to help maintain body temperature in warmer environments. Regulating body temperatures due to a change in a person's activity level in these conditions is usually as simple as adding or subtracting additional layers of clothing, but in very extreme temperatures, this may not be enough to keep a body temperature down. In some situations, the person is unable to remove or add additional layers of clothing when their activity level changes. For example, people working in very hostile environments are not able to remove or add to their protective clothing and/or suits if they become too hot or cold.
U.S. Pat. No. 6,942,015 to Jenkins discloses a body heating/cooling apparatus with a vest having a front panel and a back panel defining a cavity therebetween. A flexible, continuous channel is disposed in serpentine fashion throughout the cavity and has adjacent portions. An inlet and an outlet are provided for infusing a fluid into the channel and for withdrawing the fluid from the channel. Unfortunately, this prior art's provided liquid cooling would quickly lose its low temperature and not provide a lasting cooling effect.
U.S. Pat. No. 5,438,707 to Horn discloses a body cooling garment to cool the human body. By pressurizing air or other compressible gases to a minimum pressure rating of 70 psi and channeling it by means of a tubing network that is incorporated into body garments such as a vest, head covers, and pants, the pressurized air can be transported and dispensed on the individual. Initial cooling is achieved by the cooling of the pressurized gas itself as it rapidly depressurizes and expands through openings in the tubing resulting in a very cold gas. This effect combines with the flow of air that is created by this expansion of pressurized gas in the vicinity of the body of an individual wearing such a garment to cool the user's body. Unfortunately, this prior art reference does not disclose a lasting cooling effect that would allow a user to use the device for extended periods of time without having to constantly refill the cooling member.
U.S. Pat. No. 5,539,934 to Ponder discloses an improved cooling apparatus for a protective helmet. The cooling apparatus employs hook and loop fastener strips to secure a bladder to the interior of the helmet. The bladder is filled with a breakable pouch of encapsulated ammonium salt surrounded by water. An annular chamber in the bladder allows free communication of the cooling medium within the chamber to allow for different heat loads at different areas of the bladder. Unfortunately, this prior art reference does not disclose an internal cooling mechanism within the helmet, and the hook and loop fastener system may allow the cooling device to detach at inconvenient times.
Accordingly, a need remains for a device to overcome the above-noted shortcomings. The present invention satisfies such a need by providing a device that is convenient and easy to use, lightweight yet durable in design, and designed for providing a means of reducing a user body temperature during physical activity.